Electrode control



Feb. 24, 1959 w. M. JONES ETAL 2,875,368

7 ELECTRODE CONTROL Filed Jan. 10, 1957 I I i INVENTORS WITNESSESWallace M. Jones and Francis M.Coin,Jr.

WW2; 2 MI ZMM ATTORNEY United States Patent ELECTRODE CONTROL Wallace M.Jones, Clairton, and Francis M. Cain, Jr.,

Washington, Pa., assignors to Westinghouse Electric Corporation, EastPittsburgh, Pa a corporation of Pennsylvania Application January 10,1957, Serial No. 633,455 8 Claims. (Cl. 314-74) automatic control of thespacing of electrodes for an electric arc which is responsive to theunbalance between the arc voltage and a fixed reference voltage forcorrespondingly moving the electrodes.

' A more specific object of this invention is to control a reversiblemotor driving at least one electrode of an, electric are by a novelarrangement including a polarized relay, having its coil subjected tothe voltage of the arc in opposition to a fixed predetermined referencevoltage.

These and other objects of this invention will become more apparent uponconsideration of the following detailed description of one embodimentthereof, when taken in connection with the attached drawing in which thesingle figure illustrates diagrammatically, apparatus for operating anelectric arc lamp including the circuit con-,

nections therefor.

The electric arc lamp control apparatus illustrated on the drawing isadapted to be energized by a pair of alternating current supplyconductors 2, which may be connected to a double pole switch 4 forselectively ener gizing and deenergizing the apparatus. The switchv 4may be connected to a pair of conductors 6, which may in turn beconnected to fuses 8 for interrupting the supply of current in the eventof an overload or short circuit in the apparatus. The fuses 8 areconnected by conductors-10 to a full-wave rectifier 12, to provide asource of direct current power at the positive terminal 14 and negativeterminal 16. Preferably, a capacitor 13 is connected across therectifier terminals to smooth the rectifier Output.

The are light is adapted to be energized from the direct, currentsource, and for this purpose there is provided a conductor 18 leadingfrom one terminal 16 of the rectifier l2 and it is connected With aconductor 20, having a flexible portion 22, connected to the movableelectrode 24 of the are light. The electrode 24' may be of any suitablematerial such, for example, as carbon or the like. A second conductor 26including a regulating resistor 28 is connected from the other directcurrent output terminal him the other electrode 30 .of the are light.The electrode 3t) may be mounted on a suitable fixed support 32, whereasthe movable electrode 24 is mounted on a support 34 which is mountedformovement in a rectilinear direction toward and away from the fixedelectrode 30. Any suitable mechanical arrangement may be employed formoving the movable electrode 24 audits support 34, preferably a movementreducing means, for

for example, by a spring 51.

example, the movable support 34 may have rack teeth formed thereon forengagement with a pinion gear 36.

The movable electrode 24, and in this illustrative emhodiment of theinvention, the pinion 36, is adapted to be actuated by a reversiblealternating current motor 38. While the motor 38 may be of any desiredtype, there is illustratively depicted on the drawing a capacitor typeof motor having stator windings 40 and 42 directly connected together atone end of each winding. The other ends of the windings are joined by aconductor 62 which includes a capacitor 60, for a purpose to bedescribed. The motor 38 is adapted to be energized from the alternatingcurrent source by a means of one conductor 44 connected to one of thefuses 8 and to the directly connected ends of motor windings 40 and 42.The other side of the alternating current source of supply is connectedby means of a conductor 46 connected to the other of the fuses 8, and tothe movable confact 43 of a polarized relay 50. The movable relaycontact 48 is biased to the intermediate position shown, It will benoted that the relay 50 has one stationary contact 52 which is connectedby means of a conductor 54 directly to one of the motor windings 40, anda second stationary contact 56 is con nected by means of a conductor 58directly to the other of the motor windings 42.

The energizing circuit for the motor 48 will now be apparent as beingunder the control of the relay 50 so that when the movable contact 48 ofthe relay is in engagement with the stationary contact 52, the motorwinding 40 will be directly connected across the alternating currentsource Of supply, whereas the winding 42 will be connected in serieswith the capacitor 60 across the alternating current source of supply.This will cause the motor to operate in one direction and to drive themovable electrode 24 in one direction, for example in a direction towardthe stationary electrode 30. When the movable contact 48 of the relay isin engagement with the stationary contact 56, then the motor coil 42will be directly connected across the alternating current source ofsupply, whereas the coil 49 will be connected in series with thecapacitor 69 across the same source to thus cause operation of the motorin the reverse direction, and movement of the movable electrode 24 inthe reverse direction, for example, in the direction away from thestationary electrode 30.

In order to operate the moving contact 48 of the relay, the relayincludes a stationary magnetic core 64 adapted to be energized by awinding 66. As is Wellknown in the art, the movable contact 48 of therelay 50 isalso of a magnetic material, and is polarized so that thedirection of how of current through the winding 66 will determine theposition of movable contact 48. The relay winding 66 is connected at oneend by means of a conductor 68 to the stationary electrode 30, so as tobe at the same potential as the electrode 30, A conductor 70 connectsthe other end of the relay coil 66 to the movable element of apotentiometer 72 which is connected through a resistor 74 to theconductor 18, previously described as being directly connected to one ofthe direct current output terminals 16, and by a conductor 78 to theother of the direct current Output terminals 14 through a resistor 76.The conductor 78 thus acts to connect the coil to a potential determinedby the setting of the potentiometer 72. Both potentials appliedto'opposite ends of winding 66 are of the same polarity so that currentflow through this winding will beproportional to applies to winding 66will electrode 30 when the arc is at optimum length.

While a relatively high direct current voltage may be required to formandsustain an electric are between the electrodes 24 and 39, the actualvoltage drop across the are for optimum spacing of the electrodes willbe a lesser value, and the arc voltage will vary with variations inspacing of the arc electrodes and such voltage variations will bereflected at the end of winding 66 connected to the conductor 68.

Now if it be assumed that the lamp is not in operation, but theelectrodes are separated from each other, if it is desired to operatethe arc, the switch 4 may be closed, thus energizing the circuit. Thiswill apply a voltage to the winding 66 of relay 5e by way of conductor70 which is determined by the setting of the potentiometer 72, and thiswill be continuously applied to the winding 66 so long as the switch 4is closed. At the same time, the winding 66 of the relay 50 is subjectedto the voltage of the electrode 30, and since the electrodes are nowseparated and no current flow occurs, this voltage drop will beconsiderably higher than that referred to above as being continuouslyapplied to the winding 66, to cause a resultant current through the coilin a direction to operate the movable contact 48 into engagement withthe stationary contact 52 to cause operation of the motor 38 in adirection to move the movable electrode 24 toward the stationaryelectrode 30 and ultimately into engagement therewith. At the time theelectrodes 24 and 30 engage, the voltagedrop thereacross will decreaseto substantially zero, at which time the continuously appliedpredetermined voltage due to conductor 70 will become effective to causecurrent to flow in the relay winding 66 in the opposite direction tothus reverse the flux in core 64 and operate the movable contact 48 ofthe relay 50 into engagement with the other stationary contact 56 andthus cause operation of the motor 38 in the reverse direction to movethe electrode 24 away from the stationary electrode 36. As thisseparating movement of the electrodes 24 and 36 occurs, the voltage dropacross the electrodes will gradually increase, thus increasing thevoltage applied to the winding 66 by the conductor 68, and at theoptimum spacing of the electrodes 24 and 30 for light producingpurposes, this voltage will then be equal to the voltage continuallyimposed on the winding 66 by the conductor 70 in the manner previouslyindicated, and the relay contacts will open and the motor 38 will stop.In this way the relay 50 can operate to automatically initiate operationof the are light, and to automatically maintain an optimum spacing ofthe electrodes 24 and 39. The use of a polarized relay results in relayoperation without chatter of the relay contacts, and eliminates hunting.

Having described a preferred embodiment of the invention in accordancewith the patent statutes, it is desired to point out that the inventionis not to be limited to the specific circuit and construction disclosedherein,

as it will be apparent to persons skilled in the art that certainmodifications and changes may be made in this particular arrangementwithout departing from the broad spirit and scope of the invention.Thus, the motor 38 may be connected to both electrodes 24 and 36 tosimultaneously move them toward and away from each other. Similarly,instead of using a rectifier 12 to supply direct current, amotor-generator set could he used instead in which case the capacitor 13will not be needed. Accordingly, it ,is desired that the invention beinterpreted as broadly as possible in accordance with the appendedclaims.

We claim as'our invention:

' 1. Apparatus for operating an electric'arc lamp com: prising, a pairof lamp electrodes at least one of which is mounted for movement towardand away from the other, reversible motor operated means for moving atleast said one electrode in both directions, a polarized relay be equalto that applied from having an operating coil and contacts controllingthe energization'of said motor operated means to thus control thedirection of electrode movement, the aforesaid operating coil of saidrelay being connected across said electrodes so as to be subjected tothe voltage drop across said arc, and means for applying a predeterminedreference voltage of the same polarity to said relay coil and of a valuecorresponding to the voltage drop across the are for the optimum lengthof are.

2. Apparatus for operating an electric arc lamp comprising, a pair oflamp electrodes at least one of which is mounted for movement toward andaway from the other, reversible motor operated means for moving at leastsaid one electrode in both directions, a polarized relay having anoperating coil and contacts controlling the energization of said motoroperated to thus control s the direction of electrode movement, theaforesaid 09g." crating coil of said relay being connected across {s idelectrodes so as to be subjected to the voltage dropjicross said are,asource of direct current also connected! across said electrodes, andconnections from said sq iirce for applying a predetermined voltage fromsaid source to said coil of a polarity the same as that due to tlhevoltage drop across the electrodes and of a value corresponding to thevoltage drop across the are for the optimum length of are. l s' l 3.Apparatus for operating an electric arc lamp comprising, a pair of lampelectrodes at least one of which is mounted for movement other,reversible motor means for moving at least said one electrode in bothdirections adapted to be connected to a source of alternating current, apolarized relay con trolling the energization of said motor to thuscontrol the direction of rotation thereof, the operating coil of saidrelay being connected across said electrodes so as to be subjected tothe voltage drop across said are, a rectifier also adapted to beconnected to said source of alternating current, means connecting thedirect current output of said rectifier across said electrodes, andconnections from the direct current output of said rectifier forapplying a predetermined direct voltage to said coil of a polarity thesame as that due to the voltage drop across the electrodes and of avalue corresponding to the voltage drop across the are for the optimumlength of are.

4. Apparatus for operating an electric arc lamp comprising, a pair oflamp electrodes at least one of which is mounted for movement toward andaway from the other, reversible motor operated means for moving at leastsaid one electrode in both directions, a polarized relay having anoperating coil and contacts controlling the energization of said motoroperated means to thus control the direction of electrode movement, theaforesaid operating coil of said relay being connected across saidelectrodes so as to be subjected to the voltage drop across said arc, asource of direct current also connected across said electrodes, voltagedividing means also connected across said source of direct current, andmeans connecting said coil to said voltage dividing means in a manner toapply a predetermined voltage fromsaid source to said coil of a polaritythe same as that due to the voltage drop across the electrodes and of avalue corresponding to the voltage drop across the are for the optimumlength of arc.

5. Apparatus for operating an electric arc lamp comprising, a pair oflamp electrodes at least one of which is mounted for movement toward andaway from the other, reversible motor operated means for moving at leastsaid one electrode in both directions, a polarized relay having anoperating coil and contacts controlling the energization of said motoroperated means to thus control the direction of electrode movement, theaforesaid operating coil of said relay being connected across saidelectrodes so as to be subjected to the voltage drop across said are, asource of direct current also connected across said electrodes, voltagedividing'means also connected toward and away from theacross said sourceof direct current and including a variable part, and means connectingsaid coil to the variable part of said voltage dividing means in amanner to apply a predetermined voltage from said source to said coil ofa polarity the same as that due to the voltage drop across theelectrodes and of a value corresponding to the voltage drop across theare for the optimum length of arc.

6. Apparatus for operating an electric arc lamp comprising, a pair oflamp electrodes at least one of which is mounted for movement toward andaway from the other, reversible motor operated means for moving at leastsaid one electrode in both directions, a polarized relay having anoperating coil and contacts controlling the energization of said motoroperated means to thus control the direction of electrode movement, theaforesaid operating coil of said relay being connected across saidelectrodes so as to be subjected to the voltage drop across said arc, asource of direct current also connected across said electrodes,resistance means also connected across said source of direct current,and means connecting said coil to an intermediate point of saidresistance means to apply a predetermined voltage from said source tosaid coil of a polarity the same as that due to the voltage drop acrossthe electrodes and of a value corresponding to the voltage drop acrossthe are for the optimum length of arc.

7. Apparatus for operating an electric arc lamp com prising, a pair oflamp electrodes at least one of which is mounted for movement toward andaway from the other, reversible motor operated means for moving at leastsaid one electrode in both directions, a polarized relay having anoperating coil and contacts controlling the energization of said motoroperated means to thus control the direction of electrode movement, theaforesaid operating coil of said relay being connected across saidelectrodes so as to be subjected to the voltage drop across said arc, a

" is mounted for movement toward and away from the other,

reversible motor operated means for moving at least said one electrodein both directions, a polarized relay including an operating coil andspaced contacts adapted to be engaged by a movable contact in responseto current flow through said coil in opposite directions, respectively,means biasing said movable contact to an intermediate open circuitposition, the operating coil of said relay being connected across saidelectrodes so as to be subjected to the voltage drop across said arc,and means for applying a predetermined reference voltage of the samepolarity to said relay coil and of a value corresponding to the voltagedrop across the arc for the optimum length of arc.

Sandelowsky Apr. 18, 1933 Gilbert Jan. 2, 1934

